Generally, a weight training machine is the one that allows an exerciser to train his or her muscles by connecting a stack of weight he or she wants to train to a wire having a handle attached thereto and pulling the handle so that the stack can be moved upward.
Such a weight training machine is shown in FIGS. 1 and 2. As shown in the drawings, above a supporting stand 1 having a base 1a is mounted a pulley 2, and a wire 3, to which a plate 4 is connected, runs on the pulley 2. The plate 4 is provided at the central lower part thereof with a fixing bar 5 with a plurality of holes formed. The supporting stand 1 is provided at the central part thereof with a pair of guides 6 in such a manner that the plate 4 can be moved up and down along the guides 6. To the guides 6 are attached movably up and down a plurality of stacks 7 each having a hole into which the fixing bar is inserted. Each of the stacks is provided at the side thereof with a hole corresponding to the hole of the fixing bar 5.
In this conventional weight training machine, the fixing bar 5 attached to the lower part of the plate 4 is inserted vertically through the hole formed in the central part of the stack, and then a fixing member 8 is inserted through the hole formed in the target stack 7 so that the fixing bar 5 can be linked to the desired weight, to connect the fixing bar 5 to the stack 7. Consequently, the weight of the weight training machine is adjustable.
Approximately twenty kinds of weight training machines that help an exerciser train his or her muscles by his or her muscle parts of the body commonly have such a device for controlling weight. However, the device for controlling weight has a complex mechanical structure depending on a property of each of the weight training machine, which results in the following inconveniences and restrictive factors.
I) When adjustment of weight of the weight training machine is required, an exerciser must bend his or her back and move his or her body to the left or the right to have access to a fixing member so that the fixing member can be disengaged, and after the desired weight has been chosen, the fixing member must be inserted again. In this case, however, not only the access to the fixing member itself is inconvenient, but also it is very difficult and inconvenient to find a very small hole of the stack to be selected and insert the fixing member into the hole after the fixing member has been accessed. Especially, it is very hard and difficult for a rehabilitant with weak and discomfort constitution to control weight of the weight training machine without help of an assistant.
II) The posture as mentioned in the aforesaid paragraph I) must be taken in order to confirm the weight currently loaded, which is very inconvenient.
III) The conventional fixing member having no locking unit may be disengaged from the stack during the weight training. At this time, no load is hanging on the handle, by which the exerciser may fall down on his or her back from the chair or the heavy handle may strike him or her on the head or the face with a result that various kinds of safety accidents may occur.
IV) The training is maintained only by the fixed weight during the weight training, which makes the exerciser feel bored, with the result that better effect of the training can not be expected.
V) The part of the device for controlling weight must be formed with the open structure. As a result, a design of the device for controlling weight is severely restricted in case that any cover is attached to the stack part.
VI) Since the stack has the structure that the fixing pin is inserted into the hole of the stack, thickness of the stack must be approximately 3 cm, which increases the weight of the unit stack to 5 kg. As a result, the weight of the weight training machine must be increased or decreased by the unit of 5 kg, which have the exerciser hold the weight of 5 kg or 10 kg by force in case that the suitable training weight of the exerciser is in the range between 5 and 10 kg.